Self-cleaning screen structure for vibratory separators



Dec. 9, 1969 n. M. SWALLOW 26,735

SELF-CLEANING SCREEN STRUCTURE FOR VIBRA'I'ORY SEPARATORS Original FiledJan. 21. 1965 2 Sheets-Sheet 1 INVENTOR. 0906245 M 51444440 D. M.SWALLOW Re. 26,736 SELF'CLEA'NING SCREEN STRUCTURE FOR VTBRATORYSEPAHATORS Original Filed Jan. 21, 1965 2 Sheets-Sheet 1 INVENTOR.M06445 M 51144440 BY fi United States Patent 26,736 SELF-CLEANING SCREENSTRUCTURE FOR VIBRATORY SEPARATORS Douglas M. Swallow, Burlington,Ontario, Canada, as-

signor to Southwestern Engineering Company, Los Angeles, Calif., acorporation of California Original No. 3,366,239, dated Jan. 30, 1968,Scr. No. 426,977, Jan. 21, 1965. Application for reissue Aug. 26, 1968,Ser. No. 793,199

Int. Cl. B07b 1/50, 1/38 U.S. Cl. 209332 Claims Matter enclosed in heavybrackets [II appears in the original patent but forms no part of thisreissue specification; matter printed in italics indicates the additionsmade by reissue.

ABSTRACT OF THE DISCLOSURE A vibratory separator having a self-cleaningscreen structure. An upper separating screen and lower supporting screenare disposed in parallel relation, and a multiplicity of cleaningelements are disposed between the screens and supported on the lowerscreen. When resting on the lower screen, the upper ends of the cleaningelements are displaced from but in close proximity to the separatingscreen. The upper ends of the cleaning elements serve to strike and wipeagainst the under portion of the separating screen for cleaningtherefrom material which clings to the separating screen. Variousstructures and configurations for the cleaning elements are disclosed,and it is preferred that they are perforated and present an open areaapproximately the same as or greater than the separating screen toprovide minimum obstruction to flow of material through the screens.

This invention relates to self cleaning screen structures for vibratoryseparators, that is, to screen structures particularly adapted for thescreening of materials which tend to seal or blind conventionalseparator screens. Included in the objects of this invention are:

First, to provide a self-cleaning screen structure wherein a pluralityof cleaning elements are retained by a supporting screen under aseparating screen, the cleaning elements having fiat upper and lower endsurfaces and are so oriented and retained between the screens that theirupper end surfaces are caused to impact flatwise against the undersideof the separating screen as the screen structure is vibrated.

Second, to provide a self-cleaning screen structure as set forth in thepreceding object, which is particularly adapted for incorporation in avibratory separator of the type employing a circular screen, and whereinvibratory movement of the separator causes the cleaning elements toprecess in a circular path about the separating screen whereby the flatends thereof move laterally as well as vertically against the separatingscreen and tend to shear material which may cling to the underside ofthe separating screen.

Third, to provide a self-cleaning screen structure, which, whileparticularly adapted for circular screen type of separators, is alsoadapted for use in conjunction with separators of the rectangular type.

Fourth, to provide a self-cleaning screen structure as set forth in thepreceding objects, wherein the cleaning elements are of uniform crosssection between their flat end surfaces and mutually support each otherto maintain their orientation between the screens.

Fifth, to provide a self-cleaning screen structure wherein certainembodiments of the cleaning elements are of uniform cross section andhave lateral dimensions exceeding the spacing between the separating andsupporting See screens whereby the screens maintain the cleaningelements in predetermined orientation.

Sixth, to provide a self-cleaning screen structure wherein an embodimentthereof utilizes circular cleaning elements of various diameters, someof the smaller cleaning elements being positioned within larger cleaningelements for gyratory movement therein.

Seventh, to provide a self-cleaning screen structure wherein anembodiment thereof utilizes interlocking cleaning elements of uniformcross section so arranged that the cleaning elements are retainedagainst radial separation, but are free to move axially relative to eachother.

With the above and other objects in view, as may appear hereinafter,reference is directed to the accompanying drawings in which:

FIGURE 1 is a top view of the self-cleaning screen structure with aportion of the upper screen removed and indicating by broken lines avibrator unit disposed below the screen.

FIGURE 2 is an enlarged fragmentary view thereof with the upper orseparating screen removed and showing one form of the cleaning elements,the view being taken within circle 2 of FIGURE 1.

FIGURE 3 is an enlarged fragmentary sectional view taken through 33 ofFIGURE 1 showing some of the cleaning elements in section and others inelevation.

FIGURE 4 is a diagrammatical view indicating the spatial relationship ofthe cleaning elements and the screens.

FIGURES 5, 6 and 7 are end views of modified forms of single cleaningelements.

FIGURE 8 is a transverse sectional view through 8-8 of FIGURE 7.

FIGURE 9 is a plan view of a modified form of cleaning involving aplurality of nested rings.

FIGURE 10 is a side view thereof.

FIGURE 11 is an end view showing a pair of further modified cleaningelements.

FIGURE 12 is an end view showing several still further modified forms ofcleaning elements.

Reference is first directed to FIGURES 1 through 4. The self cleaningscreen structure includes an upper separating screen I and a lowersupporting screen 2, which is of larger mesh than the separating screen.The screens are held in parallel relation by a surrounding rim 3. In theconstruction illustrated, the rim shown is circular, but may berectangular.

Interposed between the screens 1 and 2 is a multiplicity of cleaningelements 4. The cleaning elements shown in FIGURES 2 and 3 particularly,are in the form of hollow circular cylinders each having a centralperforation 5. The cleaning elements are uniform in cross section andhave fiat ends 6.

The cleaning elements may be formed of various materials depending uponthe conditions of operation. They may be formed of ceramic material,plastic material or metal. The density of the cleaning elements maydiffer depending on the conditions of operation.

It is preferred that the cleaning elements substantially fill the spacebetween the screens so that if they are small in diameter compared tothe space between the screens, they will by mutual contact, bemaintained with their axes in perpendicular relation with the screen. Itwill be noted further that when the cleaning elements rest on the lowerscreen, their upper ends are in relatively close proximity orconfronting relation with the upper screen. This distance is materiallyless than the axial length of the cleaning elements.

The cleaning elements may be solid cylinders; however, it is preferredto use hollow cylinders for the reason that the cumulative open areabetween and within the cleaning elements should approximate the openarea of the separating screen 1 and may be greater than the open area ofthe separating screen so that the cleaning elements themselves provideminimum obstruction to flow of material through the screens. It ispreferred to use a supporting screen having large mesh not only toprovide a minimal obstrution, but also to withstand the wear imposed bythe cleaning elements.

The self cleaning screen structure herein described is particularlyadapted for use in the type of vibratory circular separator shown in theseries of Miller et a1. Patents, 2,696,302, 2,753,999, 2,777,578, and2,714,961, the Mc- Causland Patent 3,035,700 and the Wright, Jr., et al.Patent 3,029,946 as well as the type of vibratory separator shown in thecopending patent application Ser. No. 426,908, filed Jan. 21, 1965.These types of separators employ at least one circular separating screenand if additional separator screens are used, they are stackedcoaxially. These types of sparators employ a vibrator involving axiallyspaced and circumferentially displaced eccentric weights 7 and 6 whichrotate around the vertical axis of the separating screen or screens. Asmore fully brought out in the aforementioned patents and application,the eccentric weights produce gyratory vibrations which make possibleeffective separation of components of material disposed on theseparating screen or screens. The material is not only vibrated by thescreen or screens, but is moved in spiral paths, either radially outwardor radially inward on the separating screen or screens. Statedotherwise, the material precesses circumferentially on the screen.

Operation of the self-cleaning screen is as follows:

When the screens 1 and 2 and the cleaning elements 4 are subjected tothe gyratory vibrations produced by the eccentric weights, the cleaningelements vibrate between the screens as indicated by the vertical vector9 indicated at one side of FIGURE 3 so that the flat upper side strikesessentially flatwise against the upper screen; that is, there is surfacecontact rather than line contact with the upper screen. This imparts avigorous movement to the upper screen which tends to work material whichmight otherwise clog the screen upwardly out of the interstices of thescreen.

In addition, the gyratory vibration produced by the eccentric wegihts,produces a horizontal component of movement reproduced by the horizontalvector 10 indicated in FIGURE 3 causing the cleaning elements to processas a mass producing a lateral sliding movement of the fiat uppersurfaces of the cleaning elements. This lateral movement appears to beextremely effective if a component of the material being separated isgreasy or fibrous, for there appears to occur a shearing action betweenthe edges of the fiat surface of the cleaning elements and the undersurface of the separating screen. Thus, for the separation of somematerials, essentially vertical travel of the cleaning elements producesthe desired result, whereas with other material, the shearing actionresulting from the precession or lateral movement of the cleaningelements is most eifective.

As indicated previously, the cleaning elements may be maintained intheir vertical orientation by mutual support, and in the case, it shouldbe noted that while it is preferred to have all of the cleaning elementsso oriented, improved operation is obtained if the majority of theelements are so oriented.

It is preferred, however, to so dimension the cleaning elements thatthey are retained in a vertical orientation by the two screens. Thus, asshown in FIGURE 4, it is preferred that the diagonal dimension Z begreater than the distance Y between the two screens, taking into accountthe excursion of the screens due to their vibration. Stated otherwise,the vertical heights of the cleaning elements are preferably onlyslightly less than the distance Y between the screens.

The transverse shape of the cleaning elements may vary substantially.For example, the cleaning elements 4 may 'be triangular as indicated by11 in FIGURE 5 and provided with convex sides 12 and a centralperforation 13 so that the cleaning elements provide a large percentageof open area.

Alternatively, the cleaning elements may be hexagonal as indicated by 14in FIGURE 6 and again provided with a central perforation 15. Due to theinteresting characteristic of the hexagonal shape, the centralperforations of the cleaning elements must be larger than in theprevious embodiments or the density of the cleaning elements reduced.

It is also feasible in some instances to utilize cleaning elements ofrelatively large diameter such as the rosette shaped elements 16 shownin FIGURES 7 and 8. In this case, each cleaning element is provided witha plurality of perforations 17.

A still further arrangement is to form the cleaning elements of anesting set of rings 18, 19, 20 and 21 as shown in FIGURE 9. Thisarrangement is particularly advantageous for use in conjunction withrectangular screens vibrated by eccentric weights arranged about ahorizontal axis, as the smaller rings within and between the largerrings tend to orbit even though the mass of rings as a whole do notprecess.

The arrangement shown in FIGURES 9 and 10 illustrates another featurewhich aids in the cleaning action of the cleaning elements. That is, therings have different masses and therefore tend to vibrate at dilferentfrequencies, and in this case, it should be noted that the otherembodiments of the cleaning elements need not be of uniform dimension ormass.

Still further, the cleaning elements may be cross shaped as indicated by22 in FIGURE 11; that is, may have radiating spokes or ribs 23, whichneed not be limited to four, but involve three or more spokes. Stillfurther, as indicated in FIGURE 12, the cleaning elements may includespokes 24 terminating in laterally directed interlocking flanges 25;that is, the cleaning elements may be so arranged so as to be joinedtogether and restrained against relative lateral or radial displacement,but remain free to vibrate axially.

In the arrangement illustrated in FIGURE 12, the cumulative end surfacesof the cleaning elements may be minimized by defining relatively largeopenings between groups of cleaning elements; that is, if the patternindicated in FIGURE 12 is expanded, hexagonal patterns with largecentral openings are formed. In addition, the linear extent of the edgesof the cleaning elements is increased so as to enhance the shearingaction when the cleaning elements are caused to move laterally as wellas to vibrate vertically.

[While particularly embodiments of this invention have been shown anddescribed, it is not intended to limit the same to the details of theconstruction set forth, but instead, the invention embraces suchchanges, modifications and equivalents of the various parts and theirrelationships as come within the purview of the appended claims] Iclaim:

1. A self-cleaning screen structure for vibratory separators,comprising: an upper separating screen adapted to receive thereonmaterial to be screened; a lower supporting screen of relatively greatermesh size than said upper screen and disposed in parallel relationtherewith; and a multiplicity of cleaning elements disposed between saidscreens and occupying the major portion of the distance therebetween,said cleaning elements being of uniform cross section and having fiatends confronting said screens such that said cleaning elements aremovable both perpendicular and parallel to said screens and when inmotion move laterally and vertically against said upper screen to shearmaterial which clings to the underside of said screen when saidvibratory separator is in operation; said cleaning elements havinglateral dimensions exceeding the distance between said screens wherebysaid screens maintain said cleaning elements oriented with theirvertical axes perpendicular to said screens and said cleaning elementshaving the form of rings of graded diameters with the rings of smalldiameter dimensioned to nest loosely with the rings of larger diameter.

2. A self-cleaning screen structure for vibratory separators,comprising: an upper separating screen adapted to receive thereonmaterial to be screened; a lower supporting screen of relatively greatermesh size than said upper screen and disposed in parallel relationtherewith; and a multiplicity of cleaning elements disposed between saidscreens and occupying the major portion of the distance therebetween,said cleaning elements being of uniform cross section and having flatends confronting said screens such that said cleaning elements aremovable both perpendicular and parallel to said screens and when inmotion move laterally and vertically against said upper screen to shearmaterial which clings to the underside of said screen when saidvibratory separator is in operation; said cleaning elements includingradiating spokes having lateral enlargements dimensioned to interlockwith adjacent cleaning elements against relative radial displacement,said cleaning elements being relatively movable both vertically andhorizontally.

3. A self-cleaning vibratory separator, comprising: an upper separatingscreen adapted to receive thereon material to be screened; a lowersupporting screen of relatively greater mesh size than said upper screenand disposed in parallel relation therewith; a multiplicity of cleaningelements disposed between said screens, said cleaning elements beinguniform in cross section and having flat ends; each of said cleaningelements, when resting by one end on said supporting screen, presentingits other end in close proximity to said separating screen; thedimensions of said cleaning elements and the spacing between saidscreens being such that said cleaning elements are restrained to aposition with their fiat ends essentially parallel to said screens; andmeans for causing gyratory vibration of said screens thereby to cause acomponent of said material to pass through said separating screen, andthe remaining component to move spirally on said separating screen, saidgyratory vibration means also causing said cleaning elements to vibratevertically and spirally between said screens thereby causing theflatupper ends of said cleaning elements to strike and wipe against theunder portion of said separating screen, said cleaning elements beingrings of graded diameters, the rings of smaller diameter beingdimensioned to nest loosely within the rings of larger diameter.

4. A self-cleaning vibratory separator comprising: an upper separatingscreen adapted to receive thereon material to be screened; a lowersupporting screen of relatively greater mesh size than said upper screenand disposed in parallel relation therewith; a multiplicity of cleaningelements disposed between said screens, said cleaning elements beinguniform in cross section and having fiat ends; each of said cleaningelements, when resting by one end on said supporting screen, presentingits other end in close proximity to said separating screen; thedimensions of said cleaning elements and the spacing between saidscreens being such that said cleaning elements are restrained to aposition with their flat ends essentially parallel to said screens; andmeans for causing gyratory vibration of said screens thereby to cause acomponent of said material to pass through said separating screen, andthe remaining component to move spirally on said separating screen, saidgyratory vibration means also causing said cleaning elements to vibratevertically and spirally between said screens thereby causing that flatupper end of said cleaning elements to strike and wipe against the underportion of said separating screen, said cleaning elements includingmeans for interlocking engagement with adjacent cleaning elements forrestraining said cleaning elements against radial separation butpermitting both perpendicular and parallel movement so said cleaningelements with respect to said screens.

5. A self-cleaning vibratory separator, comprising: an upper separatingscreen adapted to receive thereon material to be screened; a lowersupporting screen of relatively greater mesh size than said upper screenand disposed in parallel relation therewith; a multiplicity of cleaningelements disposed between said screens, said cleaning elements beinguniform in cross section and having flat ends; each of said cleaningelements, when resting by one end on said supporting screen, presentingits other end displaced from but in close proximity to said separatingscreen; the dimensions of said cleaning element and the spacing betweensaid screens being such that said cleaning elements are restrained to aposition with their fiat ends essentially parallel to said screens; andmeans, including axially spaced and circumferentially displacedeccentric weights which [rotote] rotate around the vertical axis of saidscreens, for causing gyratory vibration of said screens thereby to causea component of said material to pass through said separating screen, andthe remaining component to move spirally on said separating screen, saidgyratory vibratory means also causing said cleaning elements to vibratevertically and spirally between said screens thereby causing th flatupper ends of said cleaning elements to strike and wipe against theunder portion of said separating screen, said cleaning elements being inthe form of hollow cylinders so as to present to said screens acumulative open area within and between said cleaning elements at leastapproximating the cumulative open area of said separating screen.

References Cited The following references, cited by the Examiner, are ofrecord in the patented file of this patent or the original patent.

UNITED STATES PATENTS 961,414 6/1910 Kinsey 209387 979,685 12/1910Mumford 209-385 X 1,572,112 2/1926 Forgcson 209323 1,925,447 9/1933Keefer 209-323 FOREIGN PATENTS 650,578 12/1962 Canada.

HARRY B. THORNTON, Primary Examiner ROBERT HALPER, Assistant ExaminerUS. Cl. X.R. 209-382, 385

